arch/arm/include/asm/highmem.h

   1 #ifndef _ASM_HIGHMEM_H
   2 #define _ASM_HIGHMEM_H
   3
   4 #include <asm/kmap_types.h>
   5
   6 #define PKMAP_BASE              (PAGE_OFFSET - PMD_SIZE)
   7 #define LAST_PKMAP              PTRS_PER_PTE
   8 #define LAST_PKMAP_MASK         (LAST_PKMAP - 1)
   9 #define PKMAP_NR(virt)          (((virt) - PKMAP_BASE) >> PAGE_SHIFT)
  10 #define PKMAP_ADDR(nr)          (PKMAP_BASE + ((nr) << PAGE_SHIFT))
  11
  12 #define kmap_prot               PAGE_KERNEL
  13
  14 #define flush_cache_kmaps() \
  15         do { \
  16                 if (cache_is_vivt()) \
  17                         flush_cache_all(); \
  18         } while (0)
  19
  20 extern pte_t *pkmap_page_table;
  21
  22 extern void *kmap_high(struct page *page);
  23 extern void kunmap_high(struct page *page);
  24
  25 /*
  26  * The reason for kmap_high_get() is to ensure that the currently kmap'd
  27  * page usage count does not decrease to zero while we're using its
  28  * existing virtual mapping in an atomic context.  With a VIVT cache this
  29  * is essential to do, but with a VIPT cache this is only an optimization
  30  * so not to pay the price of establishing a second mapping if an existing
  31  * one can be used.  However, on platforms without hardware TLB maintenance
  32  * broadcast, we simply cannot use ARCH_NEEDS_KMAP_HIGH_GET at all since
  33  * the locking involved must also disable IRQs which is incompatible with
  34  * the IPI mechanism used by global TLB operations.
  35  */
  36 #define ARCH_NEEDS_KMAP_HIGH_GET
  37 #if defined(CONFIG_SMP) && defined(CONFIG_CPU_TLB_V6)
  38 #undef ARCH_NEEDS_KMAP_HIGH_GET
  39 #if defined(CONFIG_HIGHMEM) && defined(CONFIG_CPU_CACHE_VIVT)
  40 #error "The sum of features in your kernel config cannot be supported together"
  41 #endif
  42 #endif
  43
  44 #ifdef ARCH_NEEDS_KMAP_HIGH_GET
  45 extern void *kmap_high_get(struct page *page);
  46 #else
  47 static inline void *kmap_high_get(struct page *page)
  48 {
  49         return NULL;
  50 }
  51 #endif
  52
  53 /*
  54  * The following functions are already defined by <linux/highmem.h>
  55  * when CONFIG_HIGHMEM is not set.
  56  */
  57 #ifdef CONFIG_HIGHMEM
  58 extern void *kmap(struct page *page);
  59 extern void kunmap(struct page *page);
  60 extern void *__kmap_atomic(struct page *page);
  61 extern void __kunmap_atomic(void *kvaddr);
  62 extern void *kmap_atomic_pfn(unsigned long pfn);
  63 extern struct page *kmap_atomic_to_page(const void *ptr);
  64 #endif
  65
  66 #endif